It all depends on how far back the medical records are, it is many years ago, your records would be stored in old fashioned paper records, if that is the case, you may have to pay for that.
Even with a modern up to date computerized records., for the last year ,it could be hundreds of pages for you to print off at the library at 10 pence a sheet.
You will be emailed an encryption code to access your files from the Doctors.